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<a name="Basic-PowerPC-Built_002din-Functions-Available-on-ISA-2_002e05-1"></a>
<h4 class="subsubsection">6.60.22.2 Basic PowerPC Built-in Functions Available on ISA 2.05</h4>

<p>The basic built-in functions described in this section are
available on the PowerPC family of processors starting with ISA 2.05
or later.  Unless specific options are explicitly disabled on the
command line, specifying option <samp>-mcpu=power6</samp> has the effect of
enabling the <samp>-mpowerpc64</samp>, <samp>-mpowerpc-gpopt</samp>,
<samp>-mpowerpc-gfxopt</samp>, <samp>-mmfcrf</samp>, <samp>-mpopcntb</samp>,
<samp>-mfprnd</samp>, <samp>-mcmpb</samp>, <samp>-mhard-dfp</samp>, and
<samp>-mrecip-precision</samp> options.  Specify the
<samp>-maltivec</samp> option explicitly in
combination with the above options if desired.
</p>
<p>The following functions require option <samp>-mcmpb</samp>.
</p><div class="smallexample">
<pre class="smallexample">unsigned long long __builtin_cmpb (unsigned long long int, unsigned long long int);
unsigned int __builtin_cmpb (unsigned int, unsigned int);
</pre></div>

<p>The <code>__builtin_cmpb</code> function
performs a byte-wise compare on the contents of its two arguments,
returning the result of the byte-wise comparison as the returned
value.  For each byte comparison, the corresponding byte of the return
value holds 0xff if the input bytes are equal and 0 if the input bytes
are not equal.  If either of the arguments to this built-in function
is wider than 32 bits, the function call expands into the form that
expects <code>unsigned long long int</code> arguments
which is only available on 64-bit targets.
</p>
<p>The following built-in functions are available
when hardware decimal floating point
(<samp>-mhard-dfp</samp>) is available:
</p><div class="smallexample">
<pre class="smallexample">void __builtin_set_fpscr_drn(int);
_Decimal64 __builtin_ddedpd (int, _Decimal64);
_Decimal128 __builtin_ddedpdq (int, _Decimal128);
_Decimal64 __builtin_denbcd (int, _Decimal64);
_Decimal128 __builtin_denbcdq (int, _Decimal128);
_Decimal64 __builtin_diex (long long, _Decimal64);
_Decimal128 _builtin_diexq (long long, _Decimal128);
_Decimal64 __builtin_dscli (_Decimal64, int);
_Decimal128 __builtin_dscliq (_Decimal128, int);
_Decimal64 __builtin_dscri (_Decimal64, int);
_Decimal128 __builtin_dscriq (_Decimal128, int);
long long __builtin_dxex (_Decimal64);
long long __builtin_dxexq (_Decimal128);
_Decimal128 __builtin_pack_dec128 (unsigned long long, unsigned long long);
unsigned long long __builtin_unpack_dec128 (_Decimal128, int);

The <code>__builtin_set_fpscr_drn</code> builtin allows changing the three decimal
floating point rounding mode bits.  The argument is a 3-bit value.  The
argument can either be a <code>const int</code> or the value can be stored in
a variable.
The builtin uses the ISA 3.0 instruction <code>mffscdrn</code> if available.
Otherwise the builtin reads the FPSCR, masks the current decimal rounding
mode bits out and OR's in the new value.

</pre></div>

<p>The following functions require <samp>-mhard-float</samp>,
<samp>-mpowerpc-gfxopt</samp>, and <samp>-mpopcntb</samp> options.
</p>
<div class="smallexample">
<pre class="smallexample">double __builtin_recipdiv (double, double);
float __builtin_recipdivf (float, float);
double __builtin_rsqrt (double);
float __builtin_rsqrtf (float);
</pre></div>

<p>The <code>vec_rsqrt</code>, <code>__builtin_rsqrt</code>, and
<code>__builtin_rsqrtf</code> functions generate multiple instructions to
implement the reciprocal sqrt functionality using reciprocal sqrt
estimate instructions.
</p>
<p>The <code>__builtin_recipdiv</code>, and <code>__builtin_recipdivf</code>
functions generate multiple instructions to implement division using
the reciprocal estimate instructions.
</p>
<p>The following functions require <samp>-mhard-float</samp> and
<samp>-mmultiple</samp> options.
</p>
<p>The <code>__builtin_unpack_longdouble</code> function takes a
<code>long double</code> argument and a compile time constant of 0 or 1.  If
the constant is 0, the first <code>double</code> within the
<code>long double</code> is returned, otherwise the second <code>double</code>
is returned.  The <code>__builtin_unpack_longdouble</code> function is only
available if <code>long double</code> uses the IBM extended double
representation.
</p>
<p>The <code>__builtin_pack_longdouble</code> function takes two <code>double</code>
arguments and returns a <code>long double</code> value that combines the two
arguments.  The <code>__builtin_pack_longdouble</code> function is only
available if <code>long double</code> uses the IBM extended double
representation.
</p>
<p>The <code>__builtin_unpack_ibm128</code> function takes a <code>__ibm128</code>
argument and a compile time constant of 0 or 1.  If the constant is 0,
the first <code>double</code> within the <code>__ibm128</code> is returned,
otherwise the second <code>double</code> is returned.
</p>
<p>The <code>__builtin_pack_ibm128</code> function takes two <code>double</code>
arguments and returns a <code>__ibm128</code> value that combines the two
arguments.
</p>
<p>Additional built-in functions are available for the 64-bit PowerPC
family of processors, for efficient use of 128-bit floating point
(<code>__float128</code>) values.
</p>
<hr>
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<p>
Next: <a href="Basic-PowerPC-Built_002din-Functions-Available-on-ISA-2_002e06.html#Basic-PowerPC-Built_002din-Functions-Available-on-ISA-2_002e06" accesskey="n" rel="next">Basic PowerPC Built-in Functions Available on ISA 2.06</a>, Previous: <a href="Basic-PowerPC-Built_002din-Functions-Available-on-all-Configurations.html#Basic-PowerPC-Built_002din-Functions-Available-on-all-Configurations" accesskey="p" rel="prev">Basic PowerPC Built-in Functions Available on all Configurations</a>, Up: <a href="Basic-PowerPC-Built_002din-Functions.html#Basic-PowerPC-Built_002din-Functions" accesskey="u" rel="up">Basic PowerPC Built-in Functions</a> &nbsp; [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Indices.html#Indices" title="Index" rel="index">Index</a>]</p>
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